I use the two standards above for virtually all of my arena fights. I don't have a well geared (13) Traya, DR, or BSF yet so I just avoid JMLS.
Thrawn can be a helpful sub to fracture Kenobi on Rey teams, then you simply AoE with JKL as the prime target. After 2-3 his accuracy is in the toilet and he can't hit anyone, plus most of the rest of the team is dead.
Typically poke GAS, swap back to Kylo and poke Kenobi. You can try a mass assist from Hux and hope for buff immunity but it's easier with 80 Siphon for later. Then you swap back to Kylo, target JKL and AoE to start draining his Mastery.